The present invention relates to a storage system comprising a storage device system comprising a computer and a plurality of logical storage areas.
Generally, for a storage system, a computer (file system) is able to access desired files (storage areas) in a storage device system via a target device. The target device is a logical device on a storage device system recognizable as subject to access from the computer, and is provided virtually using software, or physically using hardware. The target devices are uniformly correlated to the storage areas, and the computer is able to access the desired storage area by identifying a target device using a port ID (e.g. an identifier for uniformly identifying a port called a WWN (World Wide Name)) and an LUN (Logical Unit Number).
However, when there is a limit to the number of target devices that may be provided by the storage device system, the data capacity that may be stored in the storage device system is limited by the target device count. Also, even when there is a not a de facto limit in the number of target devices that may be provided by the storage device system, the number of target devices increases together with an increase in the file count, and there is the problem that the target device resources for the storage device system are consumed.
These problems become severe when executing a point in time copy for which it is possible to reproduce the storage state of the storage device system at an identified point in time, a so-called snapshot. Specifically, the storage device system is a system for storing data sent successively from the client computer, and when the target device resources decrease due to an increase in the number of snapshot files, the number of target devices to be allocated to the new storage areas for storing data written from the client computer also decreases. Also, when there is a limit to the number of target devices, even when there are sufficient empty areas for storing the data in the storage device system, the storage device system may not store the information originally to be stored, and there is the risk of hindrance to the function to be provided by the storage device system for storing the snapshot files.